EP0410868B1 - Supraleitende Dünnschicht aus Oxid und Verfahren zu deren Herstellung - Google Patents

Supraleitende Dünnschicht aus Oxid und Verfahren zu deren Herstellung Download PDF

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Publication number
EP0410868B1
EP0410868B1 EP90402121A EP90402121A EP0410868B1 EP 0410868 B1 EP0410868 B1 EP 0410868B1 EP 90402121 A EP90402121 A EP 90402121A EP 90402121 A EP90402121 A EP 90402121A EP 0410868 B1 EP0410868 B1 EP 0410868B1
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Prior art keywords
thin film
substrate
superconducting thin
bi2o3
set forth
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EP90402121A
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English (en)
French (fr)
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EP0410868A2 (de
EP0410868A3 (en
Inventor
Keizo Harada
Hideo Itozaki
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Sumitomo Electric Industries Ltd
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Sumitomo Electric Industries Ltd
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment
    • H10N60/0268—Manufacture or treatment of devices comprising copper oxide
    • H10N60/0296—Processes for depositing or forming copper oxide superconductor layers
    • H10N60/0381—Processes for depositing or forming copper oxide superconductor layers by evaporation, e.g. MBE
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment
    • H10N60/0268—Manufacture or treatment of devices comprising copper oxide
    • H10N60/0296—Processes for depositing or forming copper oxide superconductor layers
    • H10N60/0576—Processes for depositing or forming copper oxide superconductor layers characterised by the substrate
    • H10N60/0632—Intermediate layers, e.g. for growth control
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/922—Static electricity metal bleed-off metallic stock
    • Y10S428/9265—Special properties
    • Y10S428/93—Electric superconducting
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/70—High TC, above 30 k, superconducting device, article, or structured stock
    • Y10S505/701—Coated or thin film device, i.e. active or passive
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/70—High TC, above 30 k, superconducting device, article, or structured stock
    • Y10S505/701—Coated or thin film device, i.e. active or passive
    • Y10S505/702—Josephson junction present
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/70—High TC, above 30 k, superconducting device, article, or structured stock
    • Y10S505/701—Coated or thin film device, i.e. active or passive
    • Y10S505/703—Microelectronic device with superconducting conduction line
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/70—High TC, above 30 k, superconducting device, article, or structured stock
    • Y10S505/704—Wire, fiber, or cable

Definitions

  • the present invention relates to a superconducting thin film of compound oxide and a process for preparing the same. More particularly, it relates to an improved superconducting thin film of Bi-containing compound oxide deposited on a substrate and a process for preparing the same.
  • oxide superconductors When oxide superconductors are utilized in electronics devices or the like, it is indispensable to prepare their thin films. Thin films of the compound oxides deposited on single crystal substrates of oxides such as SrTiO3, MgO or the like exhibits relatively higher superconducting property because of the following reasons:
  • Film formation of these oxide superconductors is effected usually by physical vapour deposition technique such as sputtering, ion-plating and chemical vapour deposition technique such as MO-CVD.
  • oxide superconductor thin films prepared by known processes are difficultly applicable to electronics devices because their surfaces are not smooth. Such surface unevenness of superconductor thin film may be caused by influence of surface roughness of the substrates and by mismatch of lattice constants between substrate crystal and superconductor crystal.
  • the surface of the single crystal substrate of oxide is not smooth in the atomic level.
  • its diffraction pattern observed by a relative high-energy electron diffraction analyzer (RHEED) is a spotty pattern but is not streaky pattern which reflect surface smoothness.
  • the mismatch of lattice constants between substrate crystal and superconductor crystal is another cause of surface unevenness because a stress in the thin film which can be absorbed at an early stage of film formation is released when the thin film becomes thicker.
  • U.S. patent No. 4,837,609 proposes to insert a layer of W, Mo or Ta between a superconducting compound oxide layer and a silicon single crystal substrate.
  • Japanese patent laid-open No. 63-239,840 proposes to oxidize a copper substrate to form a CuO layer thereon and then a superconducting compound oxide layer is deposited on the CuO layer.
  • an object of the present invention is to solve the problems of known processes and to provide an improved oxide superconductor thin film having a smooth surface.
  • the present invention provides a superconducting thin film of Bi-containing compound oxide deposited on a substrate, characterized in that a buffer layer made of Bi2O3 is interposed between the superconducting thin film and the substrate.
  • following compositions are preferable:
  • These Bi-containing compound oxides are preferably of a single crystal. Thickness of these Bi-containing compound oxides is not limited to a special value but is preferably in the order of 10 nm (100 ⁇ ) to 1 »m.
  • the substrate is preferably a single crystal substrate of oxide such as MgO, SrTiO3 and YSZ in order to facilitate epitaxial growth of the buffer layer of Bi2O3 and/or of the superconducting thin film.
  • the other substrates which can be used in the present invention include single crystals of LaGaO3, NdGaO3 and LaAlO3.
  • the film forming plane depends to the substrate used.
  • their ⁇ 100 ⁇ plane and ⁇ 110 ⁇ plane are preferably used.
  • An essence of the present invention resides in that a buffer layer made of Bi2O3 is interposed between the superconducting thin film and the substrate.
  • the buffer layer made of Bi2O3 is preferably of single crystal. Thickness of this buffer layer of Bi2O3 is preferably between 1 nm to 100 nm (10 ⁇ to 1,000 ⁇ ), more preferably between 1 nm to 10 nm (10 ⁇ to 100 ⁇ ). If the thickness of this buffer layer is not thicker than 1 nm (10 ⁇ ), satisfactory advantage of the present invention can not be obtained. To the contrary, if the thickness of this buffer layer exceeds 100 nm (1,000 ⁇ ), crystallinity of Bi2O3 in the thin film become disordered and result in that a bad influence is given to the superconducting thin film. The best crystallinity of Bi2O3 buffer layer is realized in a range of thickness between 1 nm to 100 nm (10 ⁇ to 1,000 ⁇ ) and a better advantage of the present invention is obtained in this range.
  • the Bi2O3 buffer layer according to the present invention functions to absorb unevenness of surface roughness of the substrate and to absorb the difference in lattice constant of crystals between the compound oxide superconductor and the substrate. And hence, the superconducting thin films of compound oxides according to the present invention have smooth surfaces which are advantageously applicable to electronics devices.
  • Both of the Bi2O3 buffer layer and the superconducting Bi-containing compound oxide layer can be prepared by any one of known conventional thin film forming techniques including physical vapour deposition such as molecular beam epitaxial growth (MBE), sputtering, ion-beam sputtering, and ion-plating and chemical vapour deposition (CVD).
  • MBE molecular beam epitaxial growth
  • sputtering ion-beam sputtering
  • CVD chemical vapour deposition
  • a thin film of Bi2O3 is firstly deposited on a substrate in a vacuum chamber, and then a desired superconducting thin film of Bi-containing compound oxide is deposited on the thin film of Bi2O3 in the same vacuum chamber.
  • both of the Bi2O3 and the Bi-containing compound oxide are oxides, it is necessary to supply oxygen in addition to metal elements of which the Bi-containing compound oxide is made during the film forming stage.
  • the oxygen gas is supplied directly in the neighborhood of a surface of the substrate while the metal elements are fed in a form of vapors from evaporation source(s).
  • an oxide or oxides of constituent elements of the Bi-containing compound oxide can be evaporated directly from evaporation source(s).
  • any combination of these operation modes can be used.
  • the oxygen is preferably activated by micro-wave radiation before use. Ozone may be used in place of oxygen. It is also effective to produce activated oxygen by creating a plasma discharge by means of high-frequency in a vacuum chamber.
  • Film forming conditions of the Bi-containing compound oxides are known and can be used in the process according to the present invention. Examples of film forming conditions of the Bi2O3 buffer layer are shown below but the scope of the present invention should not be limited thereto.
  • the superconducting thin films according to the present invention possess very smooth surfaces and hence improved superconducting properties, so that they can be utilized advantageously in applications of Matisoo switching elements.
  • FIG. 1 illustrates an apparatus for depositing thin films of Bi2O3 and of oxide superconductor on a substrate which can be used in the process according to the present invention.
  • Fig. 2 is a RHEED pattern of a thin film of Bi2Sr2Ca n-1 Cu n O x which was grown to a thickness of 50 nm (500 ⁇ ) in an example according to the present invention.
  • a superconducting thin film of compound oxide according to the present invention of Bi2Sr2Ca2Cu3O x was deposited on a ⁇ 100 ⁇ plane of a MgO single crystal substrate by a molecular beam epitaxy (MBE) unit illustrated in Fig. 1.
  • MBE molecular beam epitaxy
  • the MBE unit shown in Fig. 1 comprises a chamber 1 interior of which is evacuated to very high vacuum, a plurality of Kunudsen Cells (K-cells) 2 each of which can control a temperature of a vapour source 10 placed therein, a plurality of shutters 8 for controlling the amount or timing of each vapour source 10, a substrate holder 3 provided with a heater 4 for heating a substrate 5, and an oxygen gas supply pipe 6 through which oxygen excited by microwave discharge supplied from a microwave source 7.
  • K-cells Kunudsen Cells
  • the resulting thin film of Bi2O3 was observed by a RHEED analyzer to showed a streaky pattern which revealed that the Bi2O3 thin film is an epitaxially grown film of good quality.
  • Fig. 2 is a diffraction patter of the resulting superconducting thin film observed by a RHEED analyzer.
  • the diffraction patter is so streaky that it reveals such a fact that the superconducting thin film is a single crystal having a smooth surface.
  • the superconducting thin film of Bi-containing compound oxide shows higher critical temperature and higher critical current density than those that are obtained by the comparative example.
  • Example 1 was repeated but conditions were modified as following: At first, a thin film of Bi2O3 was deposited on a ⁇ 100 ⁇ plane of a SrTiO3 single crystal substrate under the following conditions:
  • the resulting thin film of Bi2O3 was an epitaxially grown film of the same high quality as Example 1.
  • the resulting superconducting thin film was a very smooth film which shows a streaky pattern.
  • the critical temperature (Tc) and the critical current density (Jc) are as follows:

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Superconductor Devices And Manufacturing Methods Thereof (AREA)

Claims (13)

  1. Supraleitende Dünnschicht aus Bi-enthaltendem Verbundoxid, das auf einem Substrat aufgebracht ist, dadurch gekennzeichnet, daß eine Pufferschicht aus Bi₂O₃ zwischen der supraleitenden Dünnschicht und dem Substrat angeordnet ist.
  2. Supraleitende Dünnschicht nach Anspruch 1, bei der die Pufferschicht aus Bi₂O₃ eine Dicke zwischen 1 nm und 100 nm (10Å und 1000Å) aufweist.
  3. Supraleitende Dünnschicht nach Anspruch 2, bei der die Pufferschicht aus Bi₂O₃ eine Dicke zwischen 1 nm und 10 nm (10Å und 100Å) aufweist.
  4. Supraleitende Dünnschicht nach einem der Ansprüche 1 bis 3, bei der die supraleitende Dünnschicht aus Bienthaltendem Verbundoxid eine Zusammensetzung aufweist, die durch die folgende Formel dargestellt wird:

            Bi₄(Sr1-x,Cax)mCunOp+y

    wobei x, m, n, p und y Zahlen sind, welche die entsprechenden Bereiche erfüllen 6 ≦ m ≦ 10,
    4 ≦ n ≦ 8, 0 < x < 1, -2 ≦ y ≦ +2, bzw. p=(6+m+n).
  5. Supraleitende Dünnschicht nach einem der Ansprüche 1 bis 4, bei der das Substrat ein Oxid-Einkristall ist.
  6. Supraleitende Dünnschicht nach Anspruch 4, bei der das Substrat ein Einkristall aus einem Oxid ist, ausgewählt aus der Gruppe umfassend MgO, SrTiO₃ und YSZ.
  7. Verfahren zur Herstellung einer supraleitenden Dünnschicht aus Bi-enthaltendem Verbundoxid, das auf einem Substrat aufgebracht ist, umfassend die Ausbildung der Dünnschicht aus Bi₂O₃ auf dem Substrat in einer Vakuumkammer durch ein Abscheideverfahren und anschließendes Ausbilden der supraleitenden Dünnschicht aus dem Bi-enthaltendem Verbundoxid auf der Dünnschicht aus Bi₂O₃ in der gleichen Vakuumkammer durch ein Abscheideverfahren.
  8. Verfahren nach Anspruch 7, bei dem das Abscheideverfahren ein Vakuum-Abscheideverfahren ist.
  9. Verfahren nach Anspruch 7 oder 8, bei dem die die Bestandteile des Bi-enthaltenden Verbundoxid bildenden Elemente aus Dampfquellen verdampft werden, während Sauerstoff direkt in der Nähe des Substrates zugeführt wird.
  10. Verfahren nach einem der Ansprüche 7 bis 9, bei dem die Dünnschicht aus Bi₂O₃ eine Dicke zwischen 1 nm und 100 nm (10Å und 1000Å) aufweist.
  11. Verfahren nach einem der Ansprüche 7 bis 10, bei dem die supraleitende Dünnschicht aus dem Bi-enthaltendem Verbundoxid eine Zusammensetzung aufweist, die durch die folgende Formel dargestellt wird:

            Bi₄(Sr1-x,Cax)mCunOp+y

    wobei x, m, n, p und y Zahlen sind, welche die entsprechenden Bereiche erfüllen 6 ≦ m ≦ 10,
    4 ≦ n ≦ 8, 0 < x < 1 und -2 ≦ y ≦ +2, bzw. p=(6+m+n).
  12. Verfahren nach einem der Ansprüche 7 bis 11, bei dem das Substrat ein Oxid-Einkristall ist.
  13. Verfahren nach Anspruch 12, bei dem das Substrat ein Einkristall aus einem Oxid ist, ausgewählt aus der Gruppe umfassend MgO, SrTiO₃ und YSZ.
EP90402121A 1989-07-24 1990-07-24 Supraleitende Dünnschicht aus Oxid und Verfahren zu deren Herstellung Expired - Lifetime EP0410868B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP191013/89 1989-07-24
JP1191013A JPH0354116A (ja) 1989-07-24 1989-07-24 複合酸化物超電導薄膜および作製方法

Publications (3)

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EP0410868A2 EP0410868A2 (de) 1991-01-30
EP0410868A3 EP0410868A3 (en) 1991-05-29
EP0410868B1 true EP0410868B1 (de) 1995-02-22

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US (1) US5135906A (de)
EP (1) EP0410868B1 (de)
JP (1) JPH0354116A (de)
CA (1) CA2021821C (de)
DE (1) DE69017112T2 (de)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04357198A (ja) * 1991-02-20 1992-12-10 Sanyo Electric Co Ltd 酸化物超電導薄膜の製造方法
JP3037514B2 (ja) * 1992-09-29 2000-04-24 松下電器産業株式会社 薄膜超伝導体及びその製造方法
JP3144104B2 (ja) * 1992-11-17 2001-03-12 住友電気工業株式会社 高品質な酸化物超電導薄膜の作製方法
DE69422666T2 (de) * 1993-07-02 2000-07-27 Sumitomo Electric Industries Verfahren zur Herstellung eines hochkristallinen, dünnen SrTiO3 Oxidfilms
EP1195732A3 (de) * 2000-10-02 2004-03-10 Werner Brauweiler Verfahren und Einrichtung zur kundenorientierten Nutzung von Identifikationssystemen
US20030036483A1 (en) * 2000-12-06 2003-02-20 Arendt Paul N. High temperature superconducting thick films
WO2003034448A1 (en) * 2000-12-06 2003-04-24 The Regents Of The University Of California Superconducting composite structures
JP4228569B2 (ja) * 2001-11-28 2009-02-25 セイコーエプソン株式会社 電子デバイス用基板の製造方法及び電子デバイスの製造方法
US6756139B2 (en) * 2002-03-28 2004-06-29 The Regents Of The University Of California Buffer layers on metal alloy substrates for superconducting tapes
US6884527B2 (en) * 2003-07-21 2005-04-26 The Regents Of The University Of California Biaxially textured composite substrates
CN100365740C (zh) * 2006-04-27 2008-01-30 西南交通大学 一种高温超导涂层导体的缓冲层

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0301962B1 (de) * 1987-07-27 1994-04-20 Sumitomo Electric Industries Limited Supraleitender Dünnfilm und Verfahren, um diesen zu präparieren
DE3853273T2 (de) * 1987-12-25 1995-10-19 Sumitomo Electric Industries Ein Halbleitersubstrat mit einem supraleitenden Dünnfilm.
US4965244A (en) * 1988-09-19 1990-10-23 Regents Of The University Of Minnesota CaF2 passivation layers for high temperature superconductors

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Publication number Publication date
DE69017112D1 (de) 1995-03-30
JPH0354116A (ja) 1991-03-08
EP0410868A2 (de) 1991-01-30
US5135906A (en) 1992-08-04
CA2021821A1 (en) 1991-01-25
EP0410868A3 (en) 1991-05-29
CA2021821C (en) 1998-04-14
DE69017112T2 (de) 1995-09-14

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